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Muduga leaping frog is first new member of its genus found in over a century

  • A new species of frog endemic to the Western Ghats, a mountain range in India that is considered a global biodiversity hotspot, is the first new addition to the genus Walkerana in more than a century.
  • There are three previously known Walkerana species: W. leptodactyla, W. diplosticta, and W. phrynoderma. The newly discovered Muduga leaping frog, Walkerana muduga, is now the fourth member of the genus.
  • “After a span of 137 years, we have discovered a new frog species within the genus Walkerana,” K. P. Dinesh, a scientist at the Zoological Survey of India and lead author of the paper describing the new species, said in a statement. “The last few species descriptions within this genus date to 1876 and 1882.”

A new species of frog endemic to the Western Ghats, a mountain range in India that is considered a global biodiversity hotspot, is the first new addition to the genus Walkerana in more than a century.

There are three previously known Walkerana species: W. leptodactyla, W. diplosticta, and W. phrynoderma. The newly discovered Muduga leaping frog, Walkerana muduga, is now the fourth member of the genus.

A specimen of the frog was collected by Dr. S. P. Vijayakumar of the Indian Institute of Science and his team in 2016. A high elevation species, Walkerana muduga was found in the Elivalmalai hill range of the Western Ghats at an altitude of 1,544 meters (about 5,065 feet) above sea level. The species was described to science in a paper published in the journal Zootaxa.

“After a span of 137 years, we have discovered a new frog species within the genus Walkerana,” K. P. Dinesh, a scientist at the Zoological Survey of India and lead author of the paper describing the new species, said in a statement. “The last few species descriptions within this genus date to 1876 and 1882.”

The Western Ghats escarpment harbors around 250 species of amphibians, more than 90% of which are endemic to the region. Until now, all of the known Walkerana species were found south of the Palghat Gap, a 30-kilometer-wide (about 19-mile-wide) valley in the Western Ghats that acts as a major biogeographic barrier. Unlike its closest relatives, however, the Muduga leaping frog was found north of the Palghat Gap.

“As a taxonomist, it is interesting to note the presence of a new species from this genus on the northern side of the Palghat gap,” Dinesh said. “Prior to this study, members of this genus were thought to be restricted to areas south of the Palghat gap alone.”

The researchers performed phylogenetic and morphological analyses to confirm that W. muduga is indeed a new species distinct from the three other Walkerana frogs. They determined that the Muduga leaping frog is “deeply divergent” from its cousins.

“First, we used molecular tools to obtain the DNA sequences for these individuals to compare them with the DNA sequences of other species within this genus,” study co-author Vijay Ramesh said in a statement. “This suggested that Walkerana muduga was genetically different from other species by almost 5% to 11% within a single gene. Second, morphological measurements were made, revealing highly divergent morphological characters when compared with other Walkerana species.”

The research team named the new species after the Mudugar indigenous community of Palghat district in India’s Kerala state, a people who speak the Muduga language.

Numerous species discoveries have been made in the Western Ghats over the last decade, but the discovery of a new species north of the Palghat gap is especially notable, according to the researchers. They write: “Recent discoveries of Fejervarya marathi from Bhamburde, northern Western Ghats by Phuge et al. 2019 (a deeply divergent lineage of the ‘rufescens clade’ within the larger Fejervaraya clade); Mysticellus franki from Suganthagiri, Wayanad Plateau by Garg & Biju, 2019 (a deeply divergent lineage of ‘Micryletta clade’ within Microhylidae) and Astrobatrachus kurichiyana from Kurchiyarmala, Wayanad Plateau by Vijayakumar et al. 2019 (a deeply divergent lineage within Natatanura) suggest that these regions could harbor hidden diversity which needs to be further explored.”

But deforestation, forest degradation, and climate change are increasing pressures on wildlife in the Western Ghats, making it imperative that efforts are made to describe and conserve the ancient and endemic species of frogs found there, the researchers note. “This discovery is a wake-up call for researchers to explore the high elevation massifs of the Western Ghats,” Dinesh said.

Walkerana muduga. Photo courtesy of S P Vijayakumar.

CITATION

• Dinesh, K. P., Vijayakumar, S. P., Ramesh, V., Jayarajan, A., Chandramouli, S. R., & Shanker, K. (2020). A deeply divergent lineage of Walkerana (Anura: Ranixalidae) from the Western Ghats of Peninsular India. Zootaxa, 4729(2), 266-276. doi:10.11646/zootaxa.4729.2.7